Surge protector



y 1966 D. P. HAMILTON 3,253,177

SURGE PROTECTOR Filed March 18, 1965 2 Sheets-Sheet 1 JmdnwwJ .Uauglas LFHamzZZun 1966 D. L. P. HAMILTON 3,253,177

SURGE PROTECTOR United States Patent 3,253,177 SURGE PROTECTOR Douglas L. P. Hamilton, 8110 N. Beach Drive, Milwaukee 17, Wis. Filed Mar. 18, 1963, Ser. No. 265,762 8 Claims. (Cl. 313-231) This invention relates to surge protectors, often called lightning arrestors, to protect telephone lines and other electrical transmission lines and instrumentalities connected therewith, against the consequence of serious voltage surges on the line. Such surges may result from various causes, including lightning discharges.-

The primary purpose and object of this invention is to provide a surge protector which is reliable in service and which is simple in design and construction so that it may be produced and sold at a fraction of the cost of surge protectors heretofore available.

Still another object of this invention is to provide a surge protector that can be easily and quickly installed, and which because of its compact design and small size is admirably suited for use in telephone installations.

Still another object of this invention is to provide a surge protector in which the main elements, other than its electrodes, can be molded of plastic material, such as polyethylene.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the. hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate several complete examples of the physical embodiments of the invention constructed according to the best modes so far devised for the practical application of the principles thereof, and in which:

FIGURE 1 is a view in longitudinal section through a surge protector constructed in accordance with this invention;

FIGURE 2 is anexploded perspective view of the surge protector shown in FIGURE 1 FIGURE 3 is a longitudinal section view through a surge protector embodying this invention in its preferred form; and

FIGURE 4 is a longitudinal section view through a surge protector illustrating another embodiment of the invention.

Referring now particularly to the accompanying drawings, the numeral 5 designates the body of the surge protector illustrated in FIGURES 1 and 2. This body is formed of suitable insulating material and is preferably a plastic molding. Any of the customary plastics conventionally used as electrical insulation may be employed, but in addition to good insulating properties the material chosen should have a degree of resilience. Polyethylene is an example of a suitable material for the body.

The body is generally cylindrical and has a cavity 6 extending longitudinally thereof, which in the construction shown in FIGURES 1 and 2 is in the form of a tauntdiameter axial well. Hence, the cavity has side wall means 7 and a bottom wall 8 which closes the cavity at one end thereof. The other end of the cavity, being the top of the well, is open.

The multi-diameter formation of the cavity provides a small diameter inner or bottom end portion 9 and a large diameter outer or top end portion 10, the two being separated by an annular inwardly directed ridge 11 which 3,253,177 Patented May 24, 1966 "ice serves to space a pair of electrodes 12 and 13 located in the opposite end portions of the cavity.

The electrodes 12 and 13 are preferably carbon discs, the former being of a size to snugly fit the small diameter end portion of the cavity and the latter being of a size to fit the large diameter end portion of the cavity. For purposes of illustration, but by no means limitation, in practice the smaller electrode would have a diameter on the order of one-fourth of an inch, at least in a surge protector designed for use With telephone circuits.

The small diameter electrode 12 is held firmly against a shoulder 14 formed by the facing side of the ridge 11, by means of a yieldable expansion device, preferably in the [form of a metal spring washer 15 interposed between the bottom wall 8- of the cavity and the adjacent face of the electrode 12. A similar yieldable expansion device 16, interposed between the electrode 13 and a plug member 17 seated in the large diameter end of the cavity serves to hold the electrode 13 firmly against a shoulder 18 formed by the other side of the ridge 11.

The spring washers 15 and 16 not only hold the electrodes firmly against their respective shoulders so that the distance between these shoulders accurately determines the gap between the electrodes, but they also serve to electrically connect the electrodes 12 and 13 with conductors 19 and 20, respectively, the conductors being soldered or otherwise attached to the. spring washers and passing through holes 21 and 22 in the wall 8 and in the plug member 17.

Attention is directed to the fact that the inner edge of the ridge 11 constitutes the smallest diameter portion of the multi-diameter well, and that the wall of the'ridge which joins its inner edge with the shoulder 18 is flared to enable the small diameter electrode 12 to be assembled with the body by simply pushing the electrode down into the well past the ridge 11 and against its spring washer 15, which of course must be inserted before the electrode is.

By'the same token and for the same reason, the mouth of the cavity flares outwardly from a constriction 23 which is located a short distance outwardly of its large diameter portion 10, and the plug member 17 is of a shape corresponding to that of the portion of the cavity in which it is received. Thus after the electrode 12 is in position and the larger electrode 13 is snapped past the constriction 23 and into its portion 10 of the cavity, and the spring washer 16 is inserted, the plug member 17 may be snapped into place to complete the assembly of the device. A detent action thus characterizes the assembly, the inner end 17 of the plug member and the constriction 23 providing the coacting of the detent. The yieldability needed for this detent action is supplied by the inherent resilience or elasticity of the material from which the body member-and preferably also the plug member-is formed, the latter, like the body member, being a plastic molding.

Obviously the conductors 19 and 20, projecting as they do from the opposite ends of the body member, provide convenient means for electrically connecting the surge protector in any instrumentality designed to receive the same, and by which one of the electrodes is electrically connected with the line and the other with ground.

In that embodiment of the invention illustrated in FIG- URE 3, the body member 5' again has a generally cylindrical shape, but the cavity 6 is essentially an open-ended bore extending all the way through the body, with its opposite end portions flared as at 25. Medially of the ends of the bore there is an inwardly directed ridge 11' with fiat opposite sides providing shoulders 26 and 27. Since the end portions of the cavity at opposite sides of the ridge 11' are of the same diameter, so likewise are the carbon electrodes 2828'. The opposing faces of the electrodes or, more specifically, the peripheral edge portions thereof, seat squarely upon the shoulders 26 and 27, and are thus very accurately spaced apart by the spacer ridge 11'.

Spring Washers 30 interposed between the electrodes and plug members 31 in the end portions of the cavity serve to hold the electrodes firmly against their respective shoulders and also electrically connect the electrodes 28-28 with conductors 32 and 32', respectively. The conductors pass through and closely fit holes in the plug members.

The plug members 31 are held in position in predetermined spacial relationship with respect to the ridge 11' by detent means, indicated generally by the numeral 33. This detent means comprises an annular bead 34 on each plug member and a mating annular groove 35 in the Wall of the bore providing the cavity.

Since the heads 34 are rounded, as shown, and not very large, and the body is formed of material having a degree of resilience, such as polyethylene, it is a simple matter to snap the plug members into place during assembly of the device. Insertion of the plug members into the opposite end portions of the cavity is, of course, facilitated by the flaring outer ends 25 of the bore, and of course should be preceded by threading the conductors through the holes therein.

Securing the plug members in position in the manner described, that is, by means of the mating beads and grooves which form the detent means 33, has the advantage of providing a weather-tight seal between each plug member and the body member, and since the conductors :closely fit the holes in the plug members through which they pass, the possibility of condensation inside the cavity is virtually precluded.

The embodiment of the invention shown in FIGURE 4 differs from that of FIGURE 3 only in the specific shape of its plug members 36 and 37 and the mating portions of the cavity or bore into which they fit, and the manner in which electrical connection is established between the electrodes and their respective lead-in conductors. The first of these differences needs no explanation, being obvious from the drawings. As to the second, it is pointed out that the electrodes are molded about the flared and separated end portions of the individual strand-s of the conductors 3838, it being understood that the conductors are of the multistrand variety. In View of this manner of effecting electrical connection between the electrodes and their conductors, the spring washers 39-39 serve only to hold their respective electrodes firmly against the locating shoulders provided by the opposite sides of a ridge 40. i

From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent to those skilled in this art that this invention provides an exceedingly simple but very reliable surge protector or lightening arrestor which, because of its particu lar design and construction lends itself well to production at a low cost, and further materially simplifies connection of the protector or arrestor into an electric circuit.

It should be noted that although polyethylene was specifically mentioned as a material from which to form the body member and plug members of the protector, other materials will readily suggest themselves to those skilled in the art, the choice being on the basis of good electrical insulating properties and an inherent resilience or elasticity to permit the plug members to be snapped into place and, in the case of that form of the invention shown in FIGURES 1 and 2, to permit the electrodes'likewise to be snapped into place. Beyond this, it is desirable fior the material chosen for the body member and plug members to be amenable toplastic molding.

The electrodes can be produced in, any conventional manner but, as indicated, are preferably formed of carbon, or at least a carbonaceous conducting material.

What is claimed as my invention is: 1. A surge protector for telephone and other electrical transmission lines comprising:

(A) a body member of insulating material having a cavity with opposite ends and side wall means;

(B) electrically insulating spacer means in the cavity between its opposite ends,

said spacer means being of such size with respect to the cross sectional size of the cavity that its presence does not preclude communication between the opposite end portions of the cavity;

(C) oppositely facing shoulders on the space-r means;

-(D) a pair of electrodes in the cavity, one at each side of said spacer means,

said electrodes having opposing faces;

(E) retainer means carried by the body member holding the electrodes in position with portions thereof bearing against said shoulders so that the distance between the oppositely facing shoulders determines the gap between the opposing faces of the electrodes, said retainer means comprising (1) a wall closing the' cavity at each end thereof,

and (2) yieldable expansion means compressed between each wall and the adjacent electrode,

one of said walls being provided by aplug member inserted into the cavity;

(F) coacting detent means on the body member and the plug member to hold the plug member in definite spacial relationship to the shoulder facing it,

said detent means permitting the plug member to be snapped into place; and

(G) conductor means electrically connected with the electrodes and extending externally of the body member to provide for connecting one of the electrodes with a transmission line and the other with ground.

2. The surge protector of claim 1, wherein (A) said yieldable means comprises electrically conductive spring washers, and wherein (B) the conductor means are connected to said spring washers so that the spring washers also serve to electrically connect the conductor means with the electrodes.

3. The surge protector of claim 1, wherein (A) the detent means consists of interengaging abutments on the body member and the plug member that must be snapped past one another during insertion of the plug member into the cavity in the body member, and wherein -(B) the body member and the plug member are formed of insulating material having sufficient resilience to permit the transient deformation thereof needed to enable the abutments to be snapped past one another.

4. The surge protector of claim 3, wherein said interenga-ging abutments are a groove in one of said memhers and a mating bead on the other member. a

S. The surge protector of claim 4, wherein the head is on and encircles the plug member and the groove is in the side wall means of the body member.

6. A surge protector for telephone and other electrical transmission lines, comprising:

(A) a generally cylindrical body member of insulating material having an axial bore therethrough;

(B) an annular ridge integral with the body member in the bore thereof between its opposite ends,

said annular ridge providing oppositely facing shoulders;

(C) an electrode in each end portion of the bore, said electrodes having opposing faces;

(D) retainer means holding the electrodes in the end portions of the bore and against the shoulders,

so that the distance between the portions of the s'houlders engaged by said electrodes determines the gap between their opposing faces, said retainer means comprising (l) a plug member inserted into each of the opposite end portions of the bore in the body member,

(2) coacting detent means on said plug members and the body member to hold the plug members in definite spacial relationship with respect to the shoulders,

(3) yieldable expansion means compressed between the electrodes and the plug members to hold the electrodes firmly against their respective shoulders, and

(4) conductor means electrically connected with the electrodes and extending externally of the body member to provide for connecting one of the electrodes with a transmission line and the other with ground.

7. The surge protector of claim 6, wherein (A) the detent means consists of annular grooves in the wall of the bore in the body member; and mating annular beads on the plug members; and wherein (B) the body member is formed of insulating material Which has sutficient resilience to permit the beads to be pushed through the end portions of the bore in the body member and into alignment with the grooves therein.

8. A surge protector for telephone and other electrical transmission lines comprising:

(A) a body member of insulating material having a multi-diameter cylindrical well therein, the inner end portion of which is smaller in diameter than its open outer end portion;

(B) an annular ridge integral with the body member in the well between its opposite end portions, the inside diameter of said ridge being somewhat smaller than the diameter of the inner end portion of the well and considerably smaller than the diameter of the open outer end portion of the well;

(C) a pair of electrodes in the well, one at each side of said ridge,

(1) one of said electrodes being of a size to snugly fit the small inner end portion of the well and hence slightly larger than the inside diameter of the ridge,

so that in the placement of said electrode in its portion of the well, said electrode must be snapped past the ridge,

(2) the other electrode being of a size to snugly fit the larger outer end portion of the well, and hence freely insertable into its portion of the well;

(E) a plug member inserted into the larger outer end portion of the well;

(F) coacting detent means on the body member and the plug member to hold the plug member in definite spacial relationship to the ridge,

said detent means permitting the plug member to be snapped into place;

(G) a spring bearing against each electrode and compressed in one case between the inner end of the well and the smaller electrode and in the other case between the plug member and the larger electrode; and

(H) conductor means electrically connected with the electrodes and extending externally of the body member to provide for connecting one of the electrodes with a transmission line and the other with ground.

References Cited by the Examiner UNITED STATES PATENTS 1,966,370 7/1934 Yesner 315-36 X 2,365,518 12/1944 Berkey 313250 X 12,947,903 8/ 1960 Westrom 3l3231 GEORGE N. WESTBY, Primary Examiner.

ROBERT SEGAL, Examiner.

S. D. SCHLOSSER, Assistant Examiner. 

1. A SURGE PROTECTOR FOR TELEPHONE AND OTHER ELECTRICAL TRANSMISSION LINES COMPRISING: (A) A BODY MEMBER OF INSULATING MATERIAL HAVING A CAVITY WITH OPPOSITE ENDS AND SIDE WALL MEANS; (B) ELECTRICALLY INSULATING SPACER MEANS IN THE CAVITY BETWEEN ITS OPPOSITE ENDS, SAID SPACER MEANS BEING OF SUCH SIZE WITH RESPECT TO THE CROSS SECTIONAL SIZE OF THE CAVITY THAT ITS PRESENCE DOES NOT PRECLUDE COMMUNICATION BETWEEN THE OPPOSITE END PORTIONS OF THE CAVITY; (C) OPPOSITELY FACING SHOULDERS ON THE SPACER MEANS; (D) A PAIR OF ELECTRODES IN THE CAVITY, ONE AT EACH SIDE OF SAID SPACERS MEANS, SAID ELECTRODES HAVING OPPOSING FACES; (E) RETAINER MEANS CARRIED BY THE BODY MEMBER HOLDING THE ELECTRODES IN POSITION WITH PORTIONS THEREOF BEARING AGAINST SAID SHOULDERS SO THAT THE DISTANCE BETWEEN THE OPPOSITELY FACING SHOULDERS DETERMINES THE GAP BETWEEN THE OPPOSING FACES OF THE ELECTRODES, SAID RETAINER MEANS COMPRISING (1) A WALL CLOSING THE CAVITY AT EACH END THEREOF, AND (2) YIELDABLE EXPANSION MEANS COMPRESSED BETWEEN EACH WALL AND THE ADJACENT ELECTRODE, ONE OF SAID WALLS BEING PROVIDED BY A PLUG MEMBER INSERTED INTO THE CAVITY; (F) COACTING DETENT MEANS ON THE BODY MEMBER AND THE PLUG MEMBER TO HOLD THE PLUG MEMBER IN DEFINIT SPACIAL RELATIONSHIP TO THE SHOULDER FACING IT, SAID DETENT MEANS PERMITTING THE PLUG MEMBER TO BE SNAPPED INTO PLACE; AND (G) CONDUCTOR MEANS ELECTRICALLY CONNECTED WITH THE ELECTRODES AND EXTENDING EXTERNALLY OF THE BODY MEMBER TO PROVIDE FOR CONNECTING ONE OF THE ELECTRODES WITH A TRANSMISSION LINE AND THE OTHER WITH GROUND. 